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data-v-06225672>lingxin</a></div> <div title="创建时间" class="date iconfont icon-riqi" data-v-06225672><a href="javascript:;" data-v-06225672>2023-02-26</a></div> <!----></div></div></div> <!----> <div class="content-wrapper"><div class="right-menu-wrapper"><div class="right-menu-margin"><div class="right-menu-title">目录</div> <div class="right-menu-content"></div></div></div> <h1><img src="">JavaScript(六)<!----></h1>  <div class="theme-vdoing-content content__default"><h1 id="javascript-四"><a href="#javascript-四" class="header-anchor">#</a> JavaScript(四)</h1> <h2 id="题目目录"><a href="#题目目录" class="header-anchor">#</a> 题目目录</h2> <ol><li><a href="#q1">写一个通用的事件侦听器函数</a></li> <li><a href="#q2">如何判断一个对象是否为数组</a></li> <li><a href="#q3">冒泡排序</a></li> <li><a href="#q4">快速排序</a></li> <li><a href="#q5">求一个字符串的字节长度</a></li> <li><a href="#q6">bind的用法，以及如何实现bind的函数和需要注意的点</a></li> <li><a href="#q7">实现一个函数clone</a></li> <li><a href="#q8">下面这个ul，如何点击每一列的时候alert其index</a></li> <li><a href="#q9">定义一个log方法，让它可以代理console.log的方法</a></li> <li><a href="#q10">输出今天的日期</a></li> <li><a href="#q11">用js实现随机选取10-100之间的10个数字，存入一个数组，并排序</a></li> <li><a href="#q12">写一段JS程序提取URL的各个GET参数</a></li> <li><a href="#q13">写一个function，清除字符串前后的空格</a></li> <li><a href="#q14">实现每隔一秒钟输出1，2，3...数字</a></li> <li><a href="#q15">实现一个函数，判断输入是不是回文字符串</a></li> <li><a href="#q16">数组扁平化处理</a></li></ol> <h3 id="q1">1. 写一个通用的事件侦听器函数</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code>markyun<span class="token punctuation">.</span>Event<span class="token operator">=</span><span class="token punctuation">{</span>
    
    <span class="token function-variable function">addEvent</span><span class="token operator">:</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">element<span class="token punctuation">,</span>type<span class="token punctuation">,</span>handler</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">if</span><span class="token punctuation">(</span>element<span class="token punctuation">.</span>addEventListener<span class="token punctuation">)</span><span class="token punctuation">{</span>
            element<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span>type<span class="token punctuation">,</span>handler<span class="token punctuation">,</span><span class="token boolean">false</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span><span class="token keyword">else</span> <span class="token keyword">if</span><span class="token punctuation">(</span>element<span class="token punctuation">.</span>attachEvent<span class="token punctuation">)</span><span class="token punctuation">{</span>
            
            element<span class="token punctuation">.</span><span class="token function">attachEvent</span><span class="token punctuation">(</span><span class="token string">'on'</span><span class="token operator">+</span>type<span class="token punctuation">,</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token function">handler</span><span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
            <span class="token punctuation">}</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
            
            element<span class="token punctuation">[</span><span class="token string">'on'</span><span class="token operator">+</span>type<span class="token punctuation">]</span><span class="token operator">=</span>handler
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    
    
    
    <span class="token comment">// 移除事件</span>
 	<span class="token function-variable function">removeEvent</span> <span class="token operator">:</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">element<span class="token punctuation">,</span> type<span class="token punctuation">,</span> handler</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
 		<span class="token keyword">if</span> <span class="token punctuation">(</span>element<span class="token punctuation">.</span>removeEventListener<span class="token punctuation">)</span> <span class="token punctuation">{</span>
 			element<span class="token punctuation">.</span><span class="token function">removeEventListener</span><span class="token punctuation">(</span>type<span class="token punctuation">,</span> handler<span class="token punctuation">,</span> <span class="token boolean">false</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 		<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>element<span class="token punctuation">.</span>datachEvent<span class="token punctuation">)</span> <span class="token punctuation">{</span>
 			element<span class="token punctuation">.</span><span class="token function">detachEvent</span><span class="token punctuation">(</span><span class="token string">'on'</span> <span class="token operator">+</span> type<span class="token punctuation">,</span> handler<span class="token punctuation">)</span><span class="token punctuation">;</span>
 		<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
 			element<span class="token punctuation">[</span><span class="token string">'on'</span> <span class="token operator">+</span> type<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
 		<span class="token punctuation">}</span>
 	<span class="token punctuation">}</span><span class="token punctuation">,</span>
        
    <span class="token comment">// 阻止事件</span>
        
        <span class="token function-variable function">stopPropagation</span><span class="token operator">:</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">ev</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            
            <span class="token keyword">if</span><span class="token punctuation">(</span>ev<span class="token punctuation">.</span>stopPropagation<span class="token punctuation">)</span><span class="token punctuation">{</span>
                ev<span class="token punctuation">.</span><span class="token function">stopPropagation</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
            <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                ev<span class="token punctuation">.</span><span class="token function">cancelBubble</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>


	<span class="token comment">// 阻止默认行为</span>
	<span class="token function-variable function">preventDefault</span><span class="token operator">:</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">event</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        
        <span class="token keyword">if</span><span class="token punctuation">(</span>event<span class="token punctuation">.</span>preventDefault<span class="token punctuation">)</span><span class="token punctuation">{</span>
            event<span class="token punctuation">.</span><span class="token function">preventDefault</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
            event<span class="token punctuation">.</span>returnValue<span class="token operator">=</span><span class="token boolean">false</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>

	<span class="token comment">// 获取事件⽬标</span>
 <span class="token function-variable function">getTarget</span> <span class="token operator">:</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">event</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
 <span class="token keyword">return</span> event<span class="token punctuation">.</span>target <span class="token operator">||</span> event<span class="token punctuation">.</span>srcElement<span class="token punctuation">;</span>
 <span class="token punctuation">}</span>


<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br><span class="line-number">57</span><br><span class="line-number">58</span><br></div></div><h3 id="q2">2.如何判断一个对象是否为数组</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">isArray</span><span class="token punctuation">(</span><span class="token parameter">val</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> val<span class="token operator">===</span><span class="token string">'object'</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        
        <span class="token keyword">return</span> <span class="token class-name">Object</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span>val<span class="token punctuation">)</span><span class="token operator">===</span><span class="token string">'[object Array]'</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><h3 id="q3">3. 冒泡排序</h3> <ul><li>每次比较相邻的两个数，如果后一个比前一个小，换位置，来个n-1次，全排好</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr<span class="token operator">=</span><span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">6</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token number">7</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">]</span>

<span class="token keyword">function</span> <span class="token function">bubbleSort</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> j<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>j<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token operator">-</span>i<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>j<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token operator">&gt;</span>arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">let</span> temp<span class="token punctuation">;</span>
                
                temp<span class="token operator">=</span>arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span>
                
                arr<span class="token punctuation">[</span>j<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token operator">=</span>arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span>
                arr<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token operator">=</span>temp
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">return</span> arr
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br></div></div><h3 id="q4">4. 快速排序</h3> <ul><li>采取二分，取出中间数，数组每次和中间数比较，小的放左边，大的放右边</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr<span class="token operator">=</span><span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">4</span><span class="token punctuation">,</span><span class="token number">6</span><span class="token punctuation">,</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token number">7</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">]</span>

<span class="token keyword">function</span> <span class="token function">quickSort</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token punctuation">]</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">let</span> midIndex<span class="token operator">=</span>Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>arr<span class="token punctuation">.</span>length<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span>
    
    <span class="token keyword">var</span> mid<span class="token operator">=</span>arr<span class="token punctuation">.</span><span class="token function">splice</span><span class="token punctuation">(</span>midIndex<span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span>
    
    <span class="token keyword">let</span> left<span class="token operator">=</span><span class="token punctuation">[</span><span class="token punctuation">]</span>
    <span class="token keyword">let</span> right<span class="token operator">=</span><span class="token punctuation">[</span><span class="token punctuation">]</span>
    
    
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token keyword">if</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token operator">&lt;</span>c<span class="token punctuation">)</span><span class="token punctuation">{</span>
            left<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
            right<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">return</span> <span class="token function">quickSort</span><span class="token punctuation">(</span>left<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>c<span class="token punctuation">,</span><span class="token function">quickSort</span><span class="token punctuation">(</span>right<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br></div></div><h3 id="q5">5. 求一个字符串的字节长度</h3> <ul><li>假设：一个英文字符占用一个字节，一个中文字符两个字节</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">getBytes</span><span class="token punctuation">(</span><span class="token parameter">str</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">var</span> len<span class="token operator">=</span>str<span class="token punctuation">.</span>length
    
    <span class="token keyword">let</span> bytes<span class="token operator">=</span>len
    
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>len<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        
        <span class="token keyword">if</span><span class="token punctuation">(</span>str<span class="token punctuation">.</span><span class="token function">charCodeAt</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token operator">&gt;</span><span class="token number">255</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            <span class="token comment">//中文字符</span>
            bytes<span class="token operator">++</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">return</span> bytes
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br></div></div><h3 id="q6">6. bind的用法，以及如何实现bind函数和需要注意的点</h3> <ul><li>bind的作用和call和apply相同，区别是call和apply是立即调用函数，而bind是返回一个函数，需要调用的时候再执行，一个简单的bind函数实现如下</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token class-name">Function</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">bind</span><span class="token operator">=</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">ctx</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">var</span> fn<span class="token operator">=</span><span class="token keyword">this</span>
    
    <span class="token keyword">return</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token function">fn</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span>ctx<span class="token punctuation">,</span>arguments<span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><h3 id="q7">7. 实现一个函数clone</h3> <blockquote><p>可以对Javascript中的5种数据类型，Number,String,Object,Array,Boolean进行复制</p></blockquote> <ul><li>递归克隆</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">clone</span><span class="token punctuation">(</span><span class="token parameter">obj</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">var</span> buf
    
    <span class="token keyword">if</span><span class="token punctuation">(</span>obj <span class="token keyword">instanceof</span> <span class="token class-name">Array</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        buf<span class="token operator">=</span><span class="token punctuation">[</span><span class="token punctuation">]</span>
        <span class="token keyword">var</span> i<span class="token operator">=</span>obj<span class="token punctuation">.</span>length
        
        <span class="token keyword">while</span><span class="token punctuation">(</span>i<span class="token operator">--</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            buf<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token operator">=</span><span class="token function">clone</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span>
        <span class="token keyword">return</span> buf
    <span class="token punctuation">}</span><span class="token keyword">else</span> <span class="token keyword">if</span> <span class="token punctuation">(</span>obj <span class="token keyword">instanceof</span> <span class="token class-name">Object</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        buf<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">}</span>
        <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">var</span> k <span class="token keyword">in</span> obj<span class="token punctuation">)</span><span class="token punctuation">{</span>
            buf<span class="token punctuation">[</span>k<span class="token punctuation">]</span><span class="token operator">=</span><span class="token function">clone</span><span class="token punctuation">(</span>obj<span class="token punctuation">[</span>k<span class="token punctuation">]</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span>
        <span class="token keyword">return</span> buf
    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
        <span class="token keyword">return</span> obj
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br></div></div><h3 id="q8">8. 下面这个ul，如何点击每一列的时候alert其index</h3> <div class="language-html line-numbers-mode"><pre class="language-html"><code><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>ul</span> <span class="token attr-name">id</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span>”test”</span><span class="token punctuation">&gt;</span></span>
 <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span>这是第⼀条<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>
 <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span>这是第⼆条<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>
 <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>li</span><span class="token punctuation">&gt;</span></span>这是第三条<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>li</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>ul</span><span class="token punctuation">&gt;</span></span>

</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><ul><li>方法一，记录属性</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> list<span class="token operator">=</span>document<span class="token punctuation">.</span><span class="token function">getElementById</span><span class="token punctuation">(</span><span class="token string">'test'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">getElementsByTagName</span><span class="token punctuation">(</span><span class="token string">'li'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span><span class="token number">3</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    list<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>index<span class="token operator">=</span>i
    
    list<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function-variable function">onclick</span><span class="token operator">=</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token function">alert</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>index<span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><ul><li>二，闭包，立即执行函数</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> lis<span class="token operator">=</span>document<span class="token punctuation">.</span><span class="token function">getElementById</span><span class="token punctuation">(</span><span class="token string">'test'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">getElementsByTagName</span><span class="token punctuation">(</span><span class="token string">'li'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">var</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span><span class="token number">3</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span>
<span class="token punctuation">{</span>
 lis<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>index<span class="token operator">=</span>i<span class="token punctuation">;</span>
 lis<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>onclick<span class="token operator">=</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">a</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 <span class="token keyword">return</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
 <span class="token function">alert</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
 <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><h3 id="q9">9. 定义一个log方法，让它可以代理console.log的方法</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">log</span><span class="token punctuation">(</span><span class="token parameter">msg</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>msg<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><ul><li>传入多个参数</li></ul> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">log</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span>console<span class="token punctuation">,</span>arguments<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h3 id="q10">10. 输出今天的日期</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> d<span class="token operator">=</span><span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">var</span> year<span class="token operator">=</span>d<span class="token punctuation">.</span><span class="token function">getFullYear</span><span class="token punctuation">(</span><span class="token punctuation">)</span>

<span class="token keyword">var</span> month<span class="token operator">=</span>d<span class="token punctuation">.</span><span class="token function">getMonth</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">1</span>

month<span class="token operator">=</span>month<span class="token operator">&lt;</span><span class="token number">10</span> <span class="token operator">?</span> <span class="token string">'0'</span><span class="token operator">+</span>month<span class="token operator">:</span>month

<span class="token keyword">var</span> day <span class="token operator">=</span> d<span class="token punctuation">.</span><span class="token function">getDate</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
 day <span class="token operator">=</span> day <span class="token operator">&lt;</span> <span class="token number">10</span> <span class="token operator">?</span> <span class="token string">'0'</span> <span class="token operator">+</span> day <span class="token operator">:</span> day<span class="token punctuation">;</span>


</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h3 id="q11">11. 用js实现随机选取10-100之间的10个数字，存入一个数组，并排序</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">var</span> arr<span class="token operator">=</span><span class="token punctuation">[</span><span class="token punctuation">]</span>

<span class="token keyword">function</span> <span class="token function">getRandom</span><span class="token punctuation">(</span><span class="token parameter">isStart<span class="token punctuation">,</span>isEnd</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    <span class="token keyword">var</span> iChoice<span class="token operator">=</span>isEnd<span class="token operator">-</span>isStart<span class="token operator">+</span><span class="token number">1</span>
    
    <span class="token keyword">return</span> Math<span class="token punctuation">.</span><span class="token function">floor</span><span class="token punctuation">(</span>Math<span class="token punctuation">.</span><span class="token function">random</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token operator">*</span>iChoice<span class="token operator">+</span>isStart
    
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">var</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span> i<span class="token operator">&lt;</span><span class="token number">10</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
 iArray<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token function">getRandom</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span><span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h3 id="q12">12. 写一段JS程序提取URL中的各个GET参数</h3> <blockquote><p>有这样一个URL：http://item.taobao.com/item.htm?a=1&amp;b=2&amp;c=3&amp;d=xxx, 请写一段JS程序提取URL中各个GET参数（参数名和参数格数不确定），将其按key-value形式返回一个JSON结构中，如{a:'1',b:'2'...}</p></blockquote> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">serilizeUrl</span><span class="token punctuation">(</span><span class="token parameter">url</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">var</span> result<span class="token operator">=</span><span class="token punctuation">{</span><span class="token punctuation">}</span>
    
    url<span class="token operator">=</span>url<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">&quot;?&quot;</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span>
    
    <span class="token keyword">var</span> map<span class="token operator">=</span>url<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">&quot;&amp;&quot;</span><span class="token punctuation">)</span>
    
    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>map<span class="token punctuation">.</span>length<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        result<span class="token punctuation">[</span>map<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">'='</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token operator">=</span>map<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">&quot;=&quot;</span><span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span>
    <span class="token punctuation">}</span>
    
    <span class="token keyword">return</span> result
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h3 id="q13">13. 写一个function,清除字符串前后空格</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">if</span><span class="token punctuation">(</span><span class="token operator">!</span>String<span class="token punctuation">.</span>prptotype<span class="token punctuation">.</span>trim<span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token class-name">String</span><span class="token punctuation">.</span>prototype<span class="token punctuation">.</span><span class="token function-variable function">trim</span><span class="token operator">=</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        
        <span class="token comment">// 以空白字符开头或者空白字符结尾的换成&quot;&quot;</span>
        <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">^\s+</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">,</span><span class="token string">&quot;&quot;</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">replace</span><span class="token punctuation">(</span><span class="token regex"><span class="token regex-delimiter">/</span><span class="token regex-source language-regex">\s+$</span><span class="token regex-delimiter">/</span></span><span class="token punctuation">,</span><span class="token string">&quot;&quot;</span><span class="token punctuation">)</span>
        
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><h3 id="q14">14. 实现每隔一秒钟输出1，2，3...数字</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span><span class="token number">10</span><span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
        <span class="token function">setTimeout</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
            
            console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>i<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span><span class="token punctuation">,</span>i<span class="token operator">*</span><span class="token number">1000</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><h3 id="q15">15. 实现一个函数，判断输入是不是回文字符串</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">isCircle</span><span class="token punctuation">(</span><span class="token parameter">str</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">typeof</span> str <span class="token operator">!==</span> <span class="token string">'string'</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token boolean">false</span>
    
    <span class="token keyword">return</span> str<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">&quot;&quot;</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">reverse</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token string">&quot;&quot;</span><span class="token punctuation">)</span><span class="token operator">===</span>str
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><h3 id="q16">16. 数组扁平化处理</h3> <div class="language-js line-numbers-mode"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">flatten</span><span class="token punctuation">(</span><span class="token parameter">arr</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
    
    <span class="token keyword">return</span> arr<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">pre<span class="token punctuation">,</span>next</span><span class="token punctuation">)</span><span class="token operator">=&gt;</span><span class="token punctuation">{</span>
        <span class="token keyword">return</span> pre<span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>Array<span class="token punctuation">.</span><span class="token function">isArray</span><span class="token punctuation">(</span>next<span class="token punctuation">)</span><span class="token operator">?</span> <span class="token function">flatten</span><span class="token punctuation">(</span>next<span class="token punctuation">)</span><span class="token operator">:</span>next<span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">,</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div></div></div>  <div class="page-edit"><div class="edit-link"><a href="https://github.com/linxin1123/vuepress-blog/edit/master/docs/08.面试/02.前端面试/01.基础篇/10.JavaScript(六).md" target="_blank" rel="noopener noreferrer">编辑</a> <span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></div> <!----> <div class="last-updated"><span class="prefix">上次更新:</span> <span class="time">2023/02/26, 19:02:51</span></div></div> <div class="page-nav-wapper"><div class="page-nav-centre-wrap"><a href="/pages/97a8a1/" class="page-nav-centre page-nav-centre-prev"><div class="tooltip">JavaScript(五)</div></a> <a href="/pages/0e436b/" class="page-nav-centre page-nav-centre-next"><div class="tooltip">JavaScript进阶(一)</div></a></div> <div class="page-nav"><p class="inner"><span class="prev">
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